T. F. Cooper duplex

Discussion in 'European & Other Pocket Watches' started by Travler1, Aug 11, 2019.

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  1. Travler1

    Travler1 Registered User
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    Hello all, I wanted to share my discovery and upcoming adventure with the included pictured watch. Hopefully it will be entertainment and knowledge for those interested. I have owned this watch since the very early 1980’s ..purchased in a cache of pockets from a gold scraper ( who didn’t want to scrap em ) gold was in the $200’s after peaking to $800 or so ....anyway the dealer sold me the “lot” of pocket watch’s for $125.00 each .....large and small 10k-18k ....take all or none.

    It is only via my accumulated knowledge shared by members on this site that I am able to post this watch I wish to thank John, Graham and Omexa for there previous posts on T. F. Cooper .

    I believe the photos mostly speak for themself. However, one cannot see the duplex escapement wheel or possibly more interesting..... down in the cave.a gleam of red. I’m not sure if I’m looking at the impulse jewel or by chance a ruby roller.

    The balance on this watch is free and will spin for 2 seconds or so ....however it is wound tight. So it’s off tomorrow for bench work ....I will be pleased to post photos of exactly what’s what upon disassembly.

    I would very much appreciate any thoughts on a ruby roller and cautions for disassembly ...regards to all. 95E90A64-CF49-4534-81E6-04257DFC6683.png 75D01671-43A4-49DB-B5B9-74BF132E05C4.png

    9E6505B2-1021-410B-8FDF-B236FB450D35.jpeg
     
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  2. Travler1

    Travler1 Registered User
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    B4C0AAAA-A1A7-4EFB-A92C-908DCE6A9332.png .....having a hard time with photos ....ehhhhh
     
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  3. gmorse

    gmorse Registered User
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    Hi Travler1,

    Unlike so many Coopers we see, this is certainly the real thing! All English duplexes started off life with a ruby locking roller but relatively few had a ruby in the impulse roller.

    Because the escape wheel acts directly on the balance, you'll have to make sure the mainspring and the maintaining power, (if it has that, which looks likely), are both completely let down before you remove the balance.

    I can't find an entry for an 'EM' incuse in Priestley's London list, and the dome doesn't have a complete set of marks, hence no date letter, but it must be prior to 1822 because the leopard has a crown. It could conceivably be a Chester assay, since the leopard also appears there, but the only possible person there is Edward Maddock II in Edmund Street, Liverpool listed as being in Gore's Directory 1815-37. A look at the outer back should solve the date issue.

    Regards,

    Graham
     
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  4. John Matthews

    John Matthews Registered User
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    A nice find.

    In my notes I have T F Cooper operating out of King William Street ~1838 which is at odds with the crowned leopard's head for pre 1822. Are we sure the case is English? - if it is then I would suggest it may have been re-cased.

    In the 1820's he was operating from Wynyat Street ...

    Pigots 1822/23 trade directory

    upload_2019-8-11_19-34-14.png

    I believe that was his earliest address, thereafter he moved to President Street, St Lukes and then Duncan Place, before 18 King William Street.

    As Graham has identified there is a incuse EM maker's mark for Chester believed to be one of the two Edward Maddocks operating in Liverpool. I have checked back to Priestley's source (Ridgeway & Priestley #2113) where there is a photograph of the mark.The font is very similar, but the separation between letters is much smaller in Ridgeway - the two letters are almost touching. The latter looks as if it was made with a single punch whereas on this case the two letters look to me as if they may have been punched separately. With the potential conflict between the address and the presence of the early leopard's head, taken with the absence of a full set of consistent hallmarks, I am leaning to this being an American case. Further photographs should establish whether it is. If it is, it in no way detracts from the movement and to my mind makes the watch all the more interesting for it.

    John
     
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  5. Travler1

    Travler1 Registered User
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    Graham & John ....here’s a sister watch which moved through the simi big Texas auction house ....it is only a few serial numbers off and was described as an 1840 make. We can use that info with a grain of salt included! Apologies for not supplying the back cover pic. It is however exactly the same markings.... one note on the initials which might be more distinctive on the back cover The initials are struck as E. M on both, more clearly seen on back cover. My thoughts were that the movement was US cased with appropriate faux marks ? I definitely bow to your thoughts and resources

    I rigged a stand to hold the watch, used a small torch to view the details ...it is a ruby roller with a steel impulse. Hopefully the roller between the teeth in not terribly chongered up. I assume Graham...that’s why you state English duplexes start their life with ruby rollers, and not always ended that way....I also assume. I’ll keep you posted on the watch’s progress ...thanks a bunch DADBB2F2-37B9-4301-94E2-5CC8C1BF4E66.png
     
  6. John Matthews

    John Matthews Registered User
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    It certainly sounds as if it is an American case. Pleased to hear you have been able to see the ruby roller.

    Very true - particularly as the Heritage Auction listing provides no information regarding how they determined ~1840. I suspect the gold case was also American and precise dating of the case was not possible. It is the address that is key, I understand from my source that he was only at that address for the 2 years until 1838. I suspect the auction house used the address in order to state ~1840 in their description.

    John
     
  7. Lychnobius

    Lychnobius Registered User

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    I am happy for Graham, or anyone else, to correct me if I am wrong, but I believe the domes of English cases were not made with a flat centre (such as we see here) until about 1850; previously they were convex overall. This may mean that the case is American, with faux English marks, and that the crowned leopard is not as true a sign of an early date as it appears to be. The dial and the back plate also suggest the middle of the century to me.

    Oliver Mundy.
     
  8. John Matthews

    John Matthews Registered User
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    Oliver

    While I believe you are correct that the flat centre design on British cases is far more commonly found in, and after, the second half of the C19th - they do occur before. Here is a John Williams hunter case with a flat centre from 1826/27.

    Notwithstanding with this particular Cooper duplex, from the evidence so far presented by the owner I think we are safe to infer that the case is American.

    John
     
  9. gmorse

    gmorse Registered User
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    Hi Oliver,

    I'm sure you're right, for the generality of cases, but like so much else in horology, there will always be exceptions, as John has pointed out. However, what we can be more certain about is what the partial hallmarks tell about their veracity, or lack of it.

    Regards,

    Graham
     
  10. Tom McIntyre

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    I am not sure how much this example contributes to the discussion, but I believe this is a very clear example of a T. F.Cooper duplex in an American case.

    I am trying to recall if I have ever seen an English duplex with a ruby impulse pin. I do have a Jacot star duplex that has both the locking jewel and the impulse jewel.

    If there is a ruby impulse is it a flat stone set in the impulse arm, or is it a jewel rod that replaces the impulse arm in the design?

    Back.jpg CapInside.jpg CapOutside.jpg Cuvette.jpg Face.jpg Front.jpg FrontInside.jpg InnerBackInside.jpg Movement.jpg MovementEdge.jpg
     
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  11. John Matthews

    John Matthews Registered User
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    Tom - I posted one here - this is what it looks like ...

    upload_2019-8-14_7-53-35.png

    upload_2019-8-14_7-54-0.png

    and here is a Cooper example ...

    upload_2019-8-14_8-0-8.png

    John
     
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  12. Tom McIntyre

    Tom McIntyre Technical Admin
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    I try to avoid being stupid, but what is the function of the roller? The long tooth rests on the upright ruby and the long sapphire receives the impulse from the upright duplex teeth.
     
  13. John Matthews

    John Matthews Registered User
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    Tom - I'm sure Graham will jump in and improve, or correct, my thoughts ....

    I assume your question is prompted by to the Cooper roller in the last photograph. I would say that in the first example I posted (signed John Burdett Gibbons) the impulse jewel looks rather vulnerable and could be damaged (particularly during service by someone with limited skills) more easily than the Cooper example, which is protected by the roller into which it is secured.

    John
     
  14. Tom McIntyre

    Tom McIntyre Technical Admin
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    I thought that might be the purpose but it seems to have no function in the operation.

    I wonder if anyone ever jeweled the impulse surface of the more common impulse arm as with a lever pallet set into the arms. That might have the drawback that the arm would have excess mass.

    Another possible use for the roller is to provide a bit better dynamic poise.

    Surely it was discussed way back when> :)
     
  15. gmorse

    gmorse Registered User
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    Hi Tom,

    I feel that's a more likely explanation, plus the circular roller is rather easier to make and what would have been most important, to polish. These design decisions weren't necessarily just empirical, there were some workers with a deep understanding of their craft.

    Regards,

    Graham
     
  16. John Matthews

    John Matthews Registered User
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    Graham - while I agree entirely with the point Tom made regarding the ability to poise and your point that design decisions were driven by understanding, I believe that the 'understanding' would have included a recognition of the resilience of the design in deployment and the background of the maker. It may not be insignificant that the earliest Cooper example with an impulse jewel I have record of is ~1860, I believe the Gibbons signed example to be a little earlier and from the examples I have seen a much rarer design. A design that I suspect did not prove to be resilient. This would explain the rarity, both in terms of the limited period of manufacture and the survival rate of those that were made. The heritage of the Cooper design, I think you would agree, is the single roller, that of the Gibbons is not so obvious to me. It appears to have different influences. Exactly which 'specialist' made these components, we do not know, but they will have determined their design from the totality of their experience.

    Incidentally, while intuitively the Cooper design might look easier to polish in its finished state. I would have thought that (most/all?) of the polishing could have ben done before the jewels were fixed - am I mistaken?

    John
     
  17. gmorse

    gmorse Registered User
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    Hi John,

    Oh yes, it would have been completely polished before being jewelled. Discs are one of the easiest shapes to polish, although there were special swing tools to polish all sorts of odd shapes.

    Regards,

    Graham
     
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  18. Tom McIntyre

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    upload_2019-8-15_10-18-34.png upload_2019-8-15_10-20-49.png
    upload_2019-8-15_10-22-14.png
    I first saw the jewel impulse arm when preparing a presentation on Charles E. Jacot during his period of being an American maker. I really like the design because it makes the mechanics so obvious. They were not all that successful, of course, and that is why they are seldom seen.
     
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  19. John Matthews

    John Matthews Registered User
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    Tom - while not wishing the discussion of the Jacot star duplex to take over the thread, I would like to understand the correspondence of the clock patent and your description, with the photographs of the actual watch movement. Your description of the patent speaks of the short ruby pins - which I take to be marked '5' on fig 4

    upload_2019-8-15_18-16-42.png

    - but the photograph of what I take to be the escape wheel of the watch, (in the previous slide), appears to be brass.

    upload_2019-8-15_18-17-36.png

    In the same slide the roller with the notch appears to be steel and I cannot decide the material used for the 'impulse arm of the balance', but it may be a jewel.

    upload_2019-8-15_18-14-38.png

    I am interested in exactly how the watch escapement was constructed.

    John
     
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  20. gmorse

    gmorse Registered User
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    Hi John,

    The parts marked '5' are the impulse teeth on the escape wheel and as you state, they do appear to be brass, machined in the normal way for a duplex. The part marked '7' is the impulse 'arm' on the balance, which may be a jewel, although it isn't in the patent drawing.

    I don't understand Tom's statement about the impulse on the Jacot being 'more favourable'; the impulse is being given at a smaller escape wheel radius and a larger balance arm radius.

    Regards,

    Graham
     
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  21. Tom McIntyre

    Tom McIntyre Technical Admin
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    The longer locking tooth provides for less friction on the locking ruby. The longer impulse arm reduces the duration or angular excursion of the impulse event. Those are the primary gains versus the traditional duplex where the same general geometry is in place, but much less extreme.

    The term clock in the patent is not intended to mean in a clock frame, just that it is an escapement for clockworks as opposed to hydraulics maybe. In the patent drawing the impulse pins are jewels and the arm is metal and most likely steel. In the actual model Jacot reversed those two to make the arm a jewel and the pins metal. I do not think he would have considered making them both jewels.

    The point of showing it was to address the time line of the ruby impulse pin. The date of the patent is 1852.
     
  22. gmorse

    gmorse Registered User
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    Hi Tom,

    A smaller impulse duration, (or lift angle), has its down side, because unlike a lever this escapement isn't ever detached, so there's always some friction somewhere. It would tend to reduce the amplitude I'd have thought. In the traditional duplex, the proportions of the two parts are reversed to produce a longer impulse duration.

    Regards,

    Graham
     
  23. Travler1

    Travler1 Registered User
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    Gentlemen, thank you for the knowledge shared and the thoughts provided. I am only the poster ....pls feel free to take the conversations where it leads.

    As far as my watch ...I will post shots of the dial plate, back of dial, as well as the ruby roller and impulse,...plus any requests

    The Cooper is presently at the watchmaker, so now a wait is required.

    Wishing you all the best, thanks again ...John
     
  24. Tom McIntyre

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    My thought, and I think it was also Jacot's, was that the ratio of diameters of the locking action and impulse action should be as high as feasible in favor of the locking to reduce the friction. The force of the mainspring is expressed in the torque on the duplex wheel arbor. The short leverage arm of the impulse gives greater force to the impulse. The longer arm on the locking means it has a "lighter" touch on the locking jewel while locked (which is essentially all the time.

    It may be more fragile than a standard design, but the mechanics look superior to me. Of course, I am not a watchmaker so I may be missing something.
     
  25. gmorse

    gmorse Registered User
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    Hi Tom,

    I don't think you are, we just look at the problem from different directions. Without a mathematical analysis of the frictional components of Jacot versus traditional duplexes it's impossible to be sure. However, the fact remains that the Jacot remained a frictional rest escapement, in spite of improvements, and as such was an evolutionary dead end at a time when the detached escapements had long established their superiority.

    Sometimes the commercial considerations outweighed all other factors in establishing the success of a design, as evidenced by the small number of Savage escapements as compared to Massey and its descendant the English lever, despite Savage's theoretical advantages. It did continue in limited use for a surprisingly long time, (as did the rack lever for different reasons), so a few makers and customers must have understood its benefits.

    Regards,

    Graham
     
  26. John Matthews

    John Matthews Registered User
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    So my understanding is that with the standard design the ratio of the impulse force to the frictional resistance, due to the force applied by the locking tooth, is smaller than that of the Jacot design, but the impulse force is applied for a longer period in the standard design.

    Is that correct?

    If it is, I cannot intuitively, and certainly not theoretically, rationalise what that would mean to the 'efficiency' of the two designs.

    John
     
  27. gmorse

    gmorse Registered User
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    Hi John,

    George Daniels goes into this in some detail in chapter 8 of 'Watchmaking', where he comments that "The best proportion of the components seems to depend on the fancy of the constructor. No two individually made watches have the same component proportions but the watches exhibit no difference in performance". He goes on to compare the geometries of three fine watches by Breguet, Morice and Jürgensen to demonstrate this, with the ratio of impulse pallet to impulse teeth ranging from 1.5:1 (Breguet), to 2.2:1 (Morice) to 2.6:1 (Jürgensen). He does mention that the friction in Breguet's roller is greater, as might be expected from his lower locking roller to locking teeth ratio, (12.5:1 as opposed to 16:1 and 18:1), and this, together with a reduced impulse angle and larger drops, leads to a greater demand for impulse power. Given that these three watches are a very small sample, Daniels' conclusion on their performance is interesting.

    Regards,

    Graham
     
  28. John Matthews

    John Matthews Registered User
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    #28 John Matthews, Aug 17, 2019
    Last edited: Aug 17, 2019
    Hi Graham - thanks for pointing me to the section in Daniels, which I'm in the process of studying.

    I think you may have made a mistake - the ratios you quote are the impulse teeth to the impulse pallet (D/C)

    My interpretation of the greater friction in the Breguet, compared to that of Jürgensen, is that the friction is inversely proportional to the escape angle (unlocking angle + the smaller impulse angle). Given the quoted unlocking angles i.e. 60 for Breguet and 80 for Jürgensen, I believe it is these that are influential because they are the larger than the impulse angle. The unlocking angle is determined by the intersection of the locking roller circle (A) and the locking teeth circle (B). The smaller the unlocking angle the greater the locking portion of the oscillation which is when the friction occurs. So I conclude that the total frictional resistance that occurs is a function of the normal force applied by the locking teeth and the locking portion of the total arc of vibration, i.e. it is not solely dependent on the force.

    John
     
  29. Tom McIntyre

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    The duration of the friction on the locking roller must be essentially the same on all duplexes. It is present whenever the tooth is resting on the jewel, which is almost all the time. The variable that affects the friction must be the normal force holding the tooth against the jewel.

    During the "backward" free rotation the tooth skips over the unlocking gap, and it is free during impulse but both of those events are very short duration in all of the duplex forms. As a guess I would say a couple percent of the total time between impulses or 98% of the time the locking tooth rests on the jewel.

    In my mind it seems pretty straightforward when viewed from the point of view of the balance rather than the escape wheel. i.e. what does the balance see when all of this is happening?
     
  30. Allan C. Purcell

    Allan C. Purcell Registered User
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    I liked the last paragraph by George Daniels piece on the Duplex escapement.

    " A form or escapement is known as the Chinese duplex has double-locking teeth. Two passing vibrations are required for each impulse vibration. When used with a wheel train of 14,000 vibrations the escapement will indicate one large advancement each second. This system was once held in high esteem by the Chinese who despised crawling seconds hands on their watches. Such escapements are bad timekeepers, but doubtless, the Chinese had sufficient tranquillity of mind not to be concerned."
     
  31. Tom McIntyre

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    I shared that view for a long time and still do for most of the highly decorated movements one sees in these watches.

    Interestingly, Jacot was pursuing a different concept. It seemed important to him that the balance beat at a high frequency and that was the justification for the design. He also made the form with up to 4 micro teeth on the locking tooth. He was exploring the "best" way to apportion the power reserve with multiple oscillations of the balance for each "beat" of the watch.

    He was also the primary proponent of filing patents on watch works in Switzerland.
     
  32. gmorse

    gmorse Registered User
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    Hi John,

    This is indeed D/C.

    And this is B/A.

    The time that the locking tooth spends in contact with the locking roller is certainly constant for a given balance frequency, but the circumferential distance it travels in one cycle depends on the roller's diameter.

    Regards,

    Graham
     
  33. Tom McIntyre

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    All of the locking rollers I have seen are as small as they can practically be and often so small as to be fragile. Do you think there is much difference between them?

    I do not recall seeing any that were "functionally" large. That is to say they seem to be made as small in diameter as they can be.

    The large supporting roller in the Cooper at the beginning of this discussion has no time keeping function in the escapement. I think we both agree that it likely is there to simplify poising.
     
  34. gmorse

    gmorse Registered User
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    Hi Tom,

    The radius of the impulse roller, or rather that of the impulse pallet, (whether it's a jewel or integral with the steel roller), is determined by the difference between the radii of the locking and impulse teeth. I agree that poising is probably the main reason for the most common disc shape.

    Regards,

    Graham
     
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  35. Tom McIntyre

    Tom McIntyre Technical Admin
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    I probably should have said disc instead of roller. The only true roller action is the locking jewel that provides the rest for the locking teeth.

    The duplex is basically a single impulse dead beat escapement. I think it is the most elegant one produced in any quantity. :)
     
  36. Travler1

    Travler1 Registered User
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    E59F4C35-6D1D-4D5D-90EA-25B33F9AF6B8.png DD341714-80B4-4565-904A-4AA072629ECC.png 3D981232-10E3-4D9F-9165-6E414FE1754E.png

    Hi all....as promised, here are the photos of the roller and impulse ....I appreciate all the help with this. However, I must admit ...u guys are too smart, as I’m lost with your technical discussions of the duplex and some of it’s design considerations .

    My understanding after researching this watch ....is that the duplex was a small step below a pocket Chronometer in the 1840’s era of timekeeping, possibly the duplex was a cut above the 1840’s lever movement’s ability to maintain a consistent rate And that they were mostly a feature of the English high end watchmakers? Can anyone guess at a ratio of detent’s and or duplex’s Their ratio of production when compared to rack lever’s or lever’s ?

    Always the best ..john
     
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  37. Tom McIntyre

    Tom McIntyre Technical Admin
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    I love your two pictures of the ruby locking stone. I was hoping I would be able to see the groove running the length of the jewel.

    This is the standard form with a steel impulse arm that receives the impulse from the upright teeth on the escape wheel. The tips of the long teeth rest on the jewel surface until the groove passes by. When the balance is turning in the opposite direction from the escape wheel, it just skips across the groove. In the other direction the tooth is released and the escape wheel turns until the next tooth drops on the locking surface. during that rotation, the upright tooth strikes the impulse arm.

    That design was much easier to understand than the lever. However the fact that the lever is detached from the energy source for most of its action is a great advantage.

    The cylinder is the earlier dead beat escapement and its weakness compared to the duplex is that the impulse is not an impact, but is a sliding push.The lever impact is also a sliding push and that complicates its execution and requires more skill in building. That may explain the success the duplex had against the early levers.

    The chronometer is very detached and uses an impact for impulse. In principle it is much superior to the others, but it suffers from the tendency to stop in rough use. After about 20 or 30 years of development and refinement, the lever performance became superior to the chronometer in skilled hands.
     
  38. John Matthews

    John Matthews Registered User
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    John - I commend the quality of the photographs. The jewel appears to be in excellent condition - as good as I have seen.

    Taken with the two photographs in post #11 above, I believe we now have in this thread the three different designs of the impulse pin found in the English duplex.

    There are a number of escapement animations available - here is the one that a number of us find the most useful, as you are able to step through the frames, which is very instructive.

    Clock-Watch: History and technique of clocks and watches

    Use the key on the left to navigate

    upload_2019-8-25_7-38-20.png

    John
     
  39. gmorse

    gmorse Registered User
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    Hi John,

    Sorry about the descent into the more esoteric recesses of escapement geometry!

    Excellent pictures of the balance, which clearly show a flattened pivot tip, which I expect is replicated on the other pivot.

    Duplexes demanded a very high degree of precision in their manufacture so were inevitably produced and sold by the expensive top end of the trade. They were regarded by many as being more desirable than the earlier levers, although whether this was because they offered any long-term advantages is debatable; the development of the lever ultimately rendered them obsolete as Tom suggested, and their non-detached nature was eventually understood to be a basic flaw. One characteristic of the detent which seems seldom to be considered is that it functions without lubrication, a most desirable feature in the days of very imperfect and unstable oils.

    I can't produce numbers but there were far more detached levers eventually made than rack levers, (which suffered from being non-detached and were subject to wear, like the duplex), followed some long way behind by duplexes and behind again by detents. However, despite their limitations rack levers did play a significant part in the flourishing of the Liverpool trade, especially in its export business to the US.

    Regards,

    Graham
     
  40. John Matthews

    John Matthews Registered User
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    #40 John Matthews, Aug 25, 2019
    Last edited: Aug 25, 2019
    John - I have been trying to tie down references to confirm the period when Cooper was at the King William address.

    Unfortunately, I have been unable to locate an entry in a trade directory, however, King William Street was constructed between 1829 and 1835, being named after King William IV and I have found evidence that Cooper was based at 18 King William Street in 1838. In that year he is listed as a contributor in 'Transactions of The Society of Arts, Manufactures and Commerce Vol 51'

    upload_2019-8-25_10-18-23.png

    and in 1839 he had moved to 6, Calthorpe Street, listed in Pigots trade directory as a watch and chronometer maker.

    upload_2019-8-25_10-21-56.png

    John
     
  41. Travler1

    Travler1 Registered User
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    Thanks John, Graham n Tom.....here are some other photos.

    My most excellent benchman and photo shooter is David at The Last Wind Up ...David deserves the credit for the above complements Now please don’t send him work ......as he must have at least a 25 year back log,...but 2049DD6D-171F-4A3F-8270-F520F926EFB8.png BE9FC059-F922-4F55-8DDA-AFA66BE690A2.png 76D12D11-BAE1-4A6D-A99B-A1F6ED89F111.png D61A564E-5E0B-4900-A2ED-311005E2B1ED.png always turns my work out quickly and professionally.
     
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  42. John Matthews

    John Matthews Registered User
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    John - a couple of points regarding your latest photographs.

    Unfortunately the ruby is slightly out of focus, but as far as i can see the longitudinal slot is still well formed.

    upload_2019-8-27_7-43-15.png

    There is also considerable reflection and glare which makes interpretation difficult - it may be worth asking your watch maker if the ruby retains its cylindrical form along its length. This photograph appears to show some wear, which was not discernable on the earlier, sharper, photograph, so it is probably due to photographic distortion.

    The plate has characteristic batch marks (see here) and the frame makers mark 'J·M'. I believe this to be that of John or Jonathon Molyneux. There were 'Molyneuxs' working both in Lancashire and London as frame and chronometer makers, at this time. I am yet to tie down the specific person.

    upload_2019-8-27_7-56-11.png

    John
     
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  43. Tom McIntyre

    Tom McIntyre Technical Admin
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    I found the second image of the duplex jewel easier to study. It becomes very large when the lightbox image is made full size.

    It takes an unusually long time to load when I click on it. (about a minute).
     
  44. Travler1

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    Hello John Matthews ...thank u for the web link to Clock-Watch ...as well as the link to a world of frame makers and batch marks.
    Am I understanding correctly that my watch was #3 of a 4 batch ? I’m seeing a group of 3 > marks with a 4th > a bit separated. I only quickly scanned the batch mark info provided ...so I’ve got some studying to do. I am happy to say in reference to your question, the ruby is straight up and down all around with exception to the notch

    ....thanks for your help John, and the same to all of the contributing posters, for great info provided on the duplex escapement and this watch specifically.
     
  45. John Matthews

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    John - batch marks are not always perfectly aligned. To be more certain of an interpretation, you really need to find a consistent set of marks on a number of the components. I would interpret your frame as the 4th in a batch of 4. If you had 3 dots roughly in a line and a 4th dot separated a little further from a line of three, and not positioned in the same line, I would interpret that as the 7th movement in a batch of 8.

    Having now done a little further research on the maker's mark I think we can discount the Lancashire Jonathon Molyneux; he who was later. All of the examples I can find of frames with this particular mark have a London connection. None of the watches have features which are normally used to infer either Lancashire or Coventry finishing. They date from the late 1830s through to the mid 1860's. It is probable that the frame originated in Lancashire and that's where the mark was applied. However, although probably less likely, I would not rule out the possibility that an anonymous Lancashire frame, or even a batch of frames, in the early stage of production, was sent to London and it/they was/were stamped there by the maker that did the majority of the work.

    Others may like to comment on this suggestion.

    John
     
  46. Travler1

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    Thank u John Mathews 4th in a 4 batch ...appreciate that...... In my efforts to understand the duplex and it’s Chronological placement in the spectrum of 1820-1840 timekeepers. I ran across the following advertisement, which mentions a duplex with compensated balance being quite accurate. I’m assuming that until the detent and possibly the duplex ...that a compensated balance was not much required, as the rate of earlier movements would not benefit from a compensated balance?

    When first examining this watch and before discovering it was a duplex. I was enthused with the balance wheel as it appeared similar to a much later... 1900-1920 time trial balance ...or at least the arms look similar ?


    Please advise ... 6E960797-2D11-4AA5-93F8-71BD176FBA5F.png 5ADB9930-3E58-4786-B19C-31EDCA982C5D.png
    In your thoughts, is this balance original to the. watch .....or possibly an upgrade as a result of later refurbishment ?

    Thanks much to all ...John
     
  47. Tom McIntyre

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    The cylinder watch was the first with significant accuracy. When well executed it is nearly up to the duplex. Some cylinders were made to "chronometer standards" in the late 18th and early 19th century. There may be some from that period with Pennington balances and there were many with compensation curbs that can deliver similar performance.
    Movement.jpg Front.jpg Back.jpg
    CaseMark.jpg
     
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  48. gmorse

    gmorse Registered User
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    Hi John,

    There's no reason to suppose that this balance isn't original. If you search for 'Pennington' you should find several threads where the family is mentioned. They were chronometer makers of distinction and they originated this type of screwed, compensated balance which became the standard for as long as steel balance springs were used. The concept of the cut compensated balance was developed rather earlier, by John Arnold and Thomas Earnshaw, who between them, (although in anything but close cooperation!), virtually invented the detent marine chronometer in the form it continued right up to the introduction of electronic means of determining longitude.

    Regards,

    Graham
     
  49. John Matthews

    John Matthews Registered User
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    John

    In following Graham's advice, a search for Pennington on the forum, will lead you to a paper in Antiquarian Horology by Mercer from 1981, 'The Penningtons and their Balances. Figure 6. taken from that paper covers the balance type to which Graham refers ...

    upload_2019-9-7_0-48-4.png
    As you will see the date of the example is 1820 a few years prior to your example. However, I think it would be true to say that the 'screw type' was uncommon in the 1820s being reserved to high quality movements - Graham will correct me if I am mistaken. My impression is that even into the 1830s many (possibly the majority) of English watches did not have compensated balances. This is not to say that the majority of the watches of that decade that you will find on this forum don't have compensated 'screw type' balances - the watches posted are biased towards mid and high quality.

    Incidentally, if you wish to learn more about English watches of this era, the Antiquarian Horology Society comes with my strong recommendation. Apart from their current publications, their WEB presence has an excellent archive of past editions of Antiquarian Horology and the BHI's Horological Journal from 1858 to 2000. The early editions of which make for fascinating reading.

    John
     
  50. gmorse

    gmorse Registered User
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    Hi John,

    Yes, I think that's true. These balances were clearly more complex and hence expensive to make, whether made by soldering the two metals together and then bending them into a circle, or machining the steel part and casting the outer brass layer onto it. This one is from an 1825 Massey V.

    Jones_balance.JPG

    Regards,

    Graham
     

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